Explosive cartridge with rigid closure means



April 1966 R. A. MEREDITH ETAL 3,246,602

EXPLOSIVE CARTRIDGE WITH RIGID CLOSURE MEANS 2 Sheets-Sheet l XI-I...

Filed July 9, 1964 FIG. 6

FIG. 2

FIG. 7

FIG.

INVENTOR.

April 1966 R. A. MEREDITH ETAL 3,246,602

EXPLOSIVE CARTRIDGE WITH RIGID CLOSURE MEANS 2 Sheets-Sheet 2 Filed July9, 1964 FIG. 4

FIG. 3

INVENTOR.

KENNETH A. CRAIG JR. IBIZA/4K0 Mo4l d), 1/?- BY ROBE/77' A. MEREDITHTHE/l? ATTORNEY FIG.5

United States Patent 3,246,602 EXPLOSIVE CARTRIDGE WITH RIGID CLOSUREMEANS Robert A. Meredith, Prairie Village, Kenneth A. Craig, Jr.,Overland Park, and Bernard F. McAvoy, In, Shawnee Mission, Kans.,assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation ofPennsylvania Filed July 9, 1964, Ser. No. 381,370 23 Claims. (Cl.102-44) This invention relates to explosive cartridges, and moreparticularly to explosive cartridges adapted for forming an exposivecolu-mn train by end-to-end coupling.

The use of a train of explosive cartridges in columnar assemblies forapplication such as seismic exploration, coal mining, quarry and metalmining, well-shooting, and various constructional functions is a commonpractice, with typical assemblies shown and described in US. Patents No.2,238,938 and No. 3,013,492. In general, a plurality of like cartridgesare formed by fabricating, as by drawing, a seamless closed-endcylindrical container of steel, providing suitable male coupling means,as screw threads, at the closed end of the container, filling thecontainer with explosives, including various blasting agents, andsecuring a closure member to the closed end. Normally the closure memberis a recessed or dished disk provided with female coupling means, asscrew threads, and which is suitably secured to the container. Normallythe securement of the closure disk is eifected by means of crimping orroll-seaming the adjacent edges of the container and the closure means.To facilitate the coupling of such cartridges or sub-sections, thefemale and male couplings are normally complementary to each other, thuspermitting the cartridges to be joined in endto-end relationship into astring or column of the cartridge units desired for a specificapplication. The train or col umn is then inserted into a boring or anexisting well-hole to the required depth, and the explosive initiated inany appropriate manner.

Since water, oil, quicksand, muck and the like are com.- monly found inborings and well holes, these cartridges or subassemblies are normallyhermetically sealed to prevent contamination of the explosive by theenvironment in which they are placed. This is particularly true wherethe explosive is water sensitive or hygroscopic in nature such as thenitrocarbonitrate or ammonium nitrate type explosives. Heretofore thecomplete fabrication of an explosive cartridge or subassembly has beenaccomplished in a single location, wherein the cartridge is formed of adrawn metal container, filled with explosive material and a'closuremember secured to the container by crimping or rollseaming the adjacentedges of the closure and container into a fluid tight seal. However,since such securement of the closure member to the container by crimpingand roll-seaming involves relative heavy equipment, which together withthe safety precaution necessary in such practice, adds to the cost ofthe cartridge. Further, since these prior art cartridges generally mustbe preformed prior to transportation to on-site application, it preventson-site loading of the cartridge with the type and quantity of explosiverequired for a desired application.

In contrast to such prior art blasting cartridges, a novel blastingassembly has been discovered which permits onsite loading of thecartridge and simple water-tight closure thereof by mere manipulation ofthe cartridge components. Broadly speaking, the closure comprises areduced throat or neck section formed in the cartridge at anintermediate portion thereof spaced from both ends, With the reducedthroat portion having a tapered configuration in the form of a truncatedcone in wh ch is seated a closure member having tapered sidewallsconforming to the inner walls of the throat section. The

3,246,602 Patented Apr. 19, 1966 closure member is adapted to be drivenand forced into welding engagement in the throat section upon theabutment or engagement of the closure member by the nose portion orclosed end of a like cartridge when it is coupled with the first saidcartridge. Accordingly, the invent-ion comprehends a hollow tubularcartridge having male coupling means, such as external screw threads, onone end of the cartridge and female coupling means, such as internalscrew threads, at the opposite open end of the cartridge which adaptsthe cartridge to be coupled to like cartridges in the explosive train.The novel closure means comprises a reduced throat section which isadjacent to and spaced from the open end which is provided with thefemale coupling means. The throat section defines a truncated cone whichtapers inwardly towards the closed end of the cartridge provided withthe male coupling means, with the open sect-ion, of the cartridge,adapted to receive a closed end of a like cartridge when it is coupledto the cartridge. A closure means which is seated in the throat sectionby insertion therein, is adapted to be driven in wedging engagement inthe throat section upon projection of the closed end of a like cartridgeinto the throat section upon coupling thereof. The necessary degree ofsealing of the cartridge can be effected by the degree in which theclosure member is wedged into the neck section during the coupling oflike cartridges together.

Accordingly, it is an object of this invention to provide a novelblasting assembly. A further object of this invention is to provide anexplosive cartridge of novel construction which can be easily and simplymanufactured, and which is adapted for on-si-te loading with subsequentsimple closure thereof in fluid-tight condition. Another object of thisinvention is to provide .an explosive cartridge of novel construct-ionadapted to be filled with an explosive which can be sealed therein fromexternal environment by simple manipulation of a closure means. Anotherobject of this invention is to provide a novel explosive cartridgehaving a novel closure means which can be sealed to the cartridge bymere coupling of the cartridge to a like cartridge. Other objects andadvantages of this invention will become more apparent from thefollowing descriptions and drawings in which:

FIGURE 1 is a side view, partly in section, illustrating one embodimentof this invention; 7

FIGURE 2 is a cross-sectional view taken along lines 11-11 of FIGURE 1;

FIGURE 3 is a side view, partly in section, illustrating one embodimentof the closure means of this invention;

FIGURE 4 is a side view, partly in section, illustrating the cooperationof like cartridges of this invention during coupling thereof intoend-to-end relationship;

FIGURE 5 is a longitudinal view illustrating a columnar assembly or atrain of the explosive cartridges of this invention coupled inend-to-end relationship;

FIGURE 6 is a cross-sectional view of an explosive booster unit adaptedfor coupling to the cartridge of this invention; and

FIGURE 7 is an end view of the explosive booster unit of FIGURE 6.

Referring to the drawing, the novel cartridge of this invention as shownin FIGURE 1 comprises a tubular container 1 which is preferably ofseamless construction, and normally provided with a closed end 2 and anopen end 3. The container may be fabricated of anymaterial which isself-sustaining and rigid enough to provide a necessary strength forinsertion into borings or welhholes for the application desired. In thisregard the container can be formed of metal such as steel or variouswaterinert polymeric materials such as phenol-formaldehyde resins,polyethylene, polystyrene, cellulose acetate, polyvinyl chloride, andthe like. In the particular form contemplated, the container shown isformed of linear polyethylene formed in any suitable manner, for exampleby blow-molding.

The cartridge container 1 is normally of cylindrical configuration so asto conform it to the cross-sectional configuration normally encounteredin borings and wellholes. As shown in the drawings, the cartridgecontainer 1 is provided with a main body portion 4 integrally connectedthrough a tapered transitional section 5 to a nose portion 6 on whichare provided suitable male coupling means, such as external male screwthreads 7 which as shown are of the double thread type. As will benoted, the closed end, or end wall, of the container is of generalconvex configuration which will adapt it for cooperative engagement witha particular closure means to be described below in conjunction withthis embodiment. However, it is to be noted that this end wall may be ofany configuration desired, for example it may be planar and of reducedcross-section which is joined to the container through a beveledtransitional portion of the container.

As indicated above the opposite end of the container 1 is open with theend portion 8 adjacent thereto provided with female coupling means suchas internal female screw threads 9 formed on the inner wall of the endsection 8. If desired and as shown, female threads 9 will also be doublethreads, and will also be complementary to the male threads 7 providedon the nose portion 6 to thus adapt the cartridge for coupling to likecartridges in endto-end relationship. If desired, and as also shown, theopen end of the container is provided with a flared portion 10 havingthe internal wall thereof complementary to the taper of transitionsection 5 so as to form a smooth continuation of one coupled cartridgeto the other. In this respect it will also be noted that the transitionportion 5 is slightly stepped to provide a shoulder 11 having a widthsubstantially that of the thickness of the container at the endmostsection 3 so as to facilitate the attainment of the smooth continuationfrom cartridge to cartridge, which are coupled together. The cartridgeof this invention is adapted for closure, in accordance with thisinvention, by means of a reduced neck section or constriction 12 havinga diameter substantially smaller than that of the container main bodyportion 4 and integral end portion 8. As shown in the drawing, thenecked or throat section 12 defines, in substance, a truncated conetapering inwardly of the container toward the closed end 2 thereof. Thespecific angle of the taper is not critical in this respect and it beingonly necessary that it be suilicient to permit a wedging action of aclosure member 13 sealed therein (and described below) to obtain afluid-tight seal desired, when the closure member is forced into theneck section 12 toward the interior of the container or cartridge.

If desired, the container 1 can be reinforced at the juncture of theneck section 12 with the main body portion 4 by means of reinforcinggussets 14 which may be formed in the container during fabricationthereof.

The closure member 13 will normally be a cylindrical member havingslightly conical or tapered walls having an angle complementary to theangle provided in the throat section 12. In the form shown, particularlyFIG- URES 1 and 3, the closure member will comprise a cupped or dishedmember which is seated in the neck section 12 so that the concavity 15thereof is disposed adjacent the open-end 3 of the container. Theclosures concavity 15 is preferably complementary to the convexityprovided on the end-wall of the nose section 6 to permit the seating ofa nose section (of a coupled like cartridge) therein in order tofacilitate the driving of the closure member 13 into reduced throatsection 12. In order to assist the attainment of the seal betweenclosure member 13 and throat section 12, the sidewalls or the entireouter surfaces of the closure member may be coated, as by spraying, withrubber compositions conventionally employed in facilitating theattainment of a seal between two members. However it is to be understoodthat such rubber coating is not necessary since an effective seal can beobtained by simple wedgement of the closure member 13 within the throatsection 12. In this respect it is noted that the provision of thetapered throat section 12 provides a secondary important function ineliminating disadvantages inherent in blow-molding of plastic materials.As is known, inherent in the process of blow-molding is the inabilityfor internal surface finishing of molded articles obtained thereby.Accordingly, a wide variation in tolerance is found to occur indimensional variation of the inner walls of the article. As will beappreciated, such dimensional variation, of the herein describedblow-molded cartridge, can be obviated by the simple expedient ofwedging the closure member 13 in the throat section 12, by only adistance necessary to compensate for variation in internal dimension ofthe throat section 12. It is also noted that the reduced neck section 12provides a further supplemental advantage in the handling of thecartridges. As will be appreciated, a continuously smooth containerinvolves difficulty in the handling thereof, as by grasping or by theuse of tools, without denting or damage thereof. In contrast, thereduced throat section 12 forms a substantial indentation or depressionin the exterior of the cartridge to permit easier grasping and holdingthereof during manipulation necessary in coupling the units togetherand/or insertion into the boring or well-hole. This is particularlysignificant when the cartridge is handled under a wet environment, whichmakes the cartridge more slippery than usual when, as commonly happens,the cartridge is handled by grease-stained gloves or hands, orparticularly when the container is formed of polyethylene as hereincontemplated.

In operation, the container 1 is filled, on-site if desired, with a maincharge 20 of an explosive, preferably capinsensitive, in an amountdesired for the specific application. The container is then closed bythe insertion of a closure member 13 through the open-end 3 of thecontainer, into the reduced throat section 12 to seat the closure membertherein. If desired, and preferably, as shown in the drawings, thedesired orientation of the closure member 13 in throat section 12 may befacilitated by and the closure member locked therein by means of adetent section 21 formed of a portion of the throat section 12, andhaving a still further reduced diameter which forms a circumferentiallyextending projection 22 which, in turn, defines an inner shoulder 23 ofa width sufficient to radially overhang the closure member 13 butinsufficient to interfere with the insertion of the closure member 13into the throat section 12. Although the projection 23, for locking theclosure member in the throat section, has been described as continuous,it is to be understood that the projection may be segmented, or formedas a plurality of circumferentially spaced lugs, in any number to effectthe desired orientation of and locking of the closure member into thethroat section. Further, although the detent section 21 has beendescribed as being a reduced diameter, it is to be understood that suchreference is made only to internal diameter thereof with the externaldiameter thereof permissably having the same external diameter as thethroat section 12.

Any cap sensitive explosive can be employed as the main charge of thecartridge, typical of which are the nitrocarbonitrate or ammoniumnitrate type explosives, with or without sensitizers. Thenitrocarbonitrate explosive may be comprised mainly of ammonium nitrateand some carbonaceous material which is combustible, examples of whichare carbon (either carbon black or in the form of coal dust), parafiins,and various liquid hydrocarbons (such as diesel oil and fuel oils), eachof which may be used either in whole or in part as the carbonaceousmaterial. The ammonium nitrate need not be of high purity and canactually be of fertilizer grade, coated or uncoated with sensitizers orother additives, and granular and free flowing. A particularly usefulcomposition may be the prilled ammonium nitrate processed and compoundedin accordance with the teachings of US. Patent No. 2,975,046. However,it is to be understood that although any cap-insensitive main explosivecharge is preferred as the main charge of the cartridge, the inventionis not limited thereby, since any type of main explosive charge can beemployed.

The cartridge or subunits of this invention can be assembled into anexplosive column (see FIGURES 4 and 5) by coupling two like cartridgestogether in end-toend relationship This assembly can be effected by theinsertion of a nose portion 6' of a like cartridge 1' into the open endof cartridge 1, and then screwing the units together by engagement ofthe male threads 7 of cartridge 1 with the female threads 9 ofcartridge 1. As can be more clearly seen in FIGURE 4, as the noseportion 6', of cartridge 1', advances within the end portion 8 ofcartridge 1, it engages closure member 13 by seating in the concavitythereof. With further advancement of the nose portion 6', it forces ordrives the closure member 13 into more severe wedgement within thereduced throat section 12 to provide the desired sealing of the maincharge 2t} from an external environment. The new position of theelements is shown in phantom in FIGURE 4 wherein the new position ofclosure member 13 is shown as 13a, and that of closed end 2' of noseportion 6' are shown respectively, as Za and 6'a. Coupling of thecartridge units may be continued to the number desired in the column, abooster unit may then be coupled to an endmost cartridge, and the axialalignment of cartridges and boosting unit may then be inserted in theboring or well-hole for subsequent initiation of the booster and maincharges.

A particularly effective explosive booster unit, also comprehened withinthis invention, is illustrated in FIG- URE 6. This booster unit maycomprise an elongated tubular container formed of the same material asthe novel cartridges described above. For example, the container may beformed of linear polyethylene by injection molding and the like. In theform shown the booster unit is provided with an integral end noseportion 31 provided thereon with a male coupling means, such as malescrew threads 32 having a configuration complementary to the femalethreads 9 of cartridge 1. However it is noted that since the boosterunit forms the terminal unit of an explosive train, there is nonecessity for further additional coupling means in order to accommodatefor further coupling of additional units, and accordingly the open endof the booster unit is therefore not provided with coupling means orscrew threads. The closed end 35 of the booster unit is formed with aninwardly extending axial recess 36 so as to form a detonator well forreceiving a detonator 37. The facilitate the threading of the lead wires38, extending from detonator 37, the booster unit is provided with alongitudinal groove 39 which communicates with detonator well 36 and theexterior of the explosive train 25. In practice the boster unit isfilled with a suitable explosive booster composition and a closuremember or cap 40, which also may be fabricated from polyethylene, issecured to the open end of the booster unit, by spin-welding and thelike. A detonator 37 may then be inserted itno the detonator well 36with the lead wires 38 threaded along groove 39, and the booster unit isthen coupled, as by screwing, to the female coupling of an endmostcartridge unit of the explosive train. It is noted that since the endportion 31 of the booster unit is complementary to the female couplingon an adjacent coupling cartridge, the end of the booster unit willproject into the nose portion of the adjacent coupled cartridge so as toabut and force and further wedge the closure member seated thereinfurther into the throat section.

Although not absolutely required, the retention of the detonator in itswell 36 can be effectively accomplished by a modification in theconfiguration of the well. As shown in the drawings, the detonator well36 can be formed in a conical form tapering inwardly of the booster unitso that the end-wall of the Well is of smaller cross-section than theentrance or mouth of the well. The cross-sectional dimensions of thewell can be sized so that it will snugly receive a variety ofcommercially available detonators when they are partially inserted inthe well, and so that the detonator can be and will be firmly wedged inthe well upon full insertion therein under nominal force such as may beapplied bodily.

Any suitable cap-sensitive composition may be employed in the boosterunit, typical of which are gelatin dynamite, trinitrotoluene, tetryl,pentaerythritol tetranitrate, picric acid and the like. The size of thebooster unit is normally small as compared with the size of the maincharge in the cartridge units. For example, by way of comparison, atypical cartridge unit of this invention was approximately 27% incheslong whereas, in contrast, the booster unit of substantially the samecorresponding cross-sectional dimensions was fabricated in a length of6% inches. Any suitable method of detonating the booster charges can beemployed such as blasting caps or detonating fuses. For example, theblasting cap may be a cornmercially available unit containing standardcharges of mercury fnlmanate.

Although the invention has been described with references to specificmaterials, embodiments and details, various modifications and changeswithin the scope of the invention will be apparent to one skilled in theart and are contemplated to be embraced within the invention.

What is claimed is:

I. In a hollow cylindrical cartridge having one closed end male couplingmeans on the one closed end thereof and female coupling means on theopposite end thereof for coupling to like cartridges into an explosivetrain, the improvement comprising, a reduced throat section defining atruncated cone tapering inwardly of said cartridge toward said closedend having said male coupling means with said throat section beingreduced relative to adjacent portions of said cartridge and spaced from,both, said closed end and said opposite end, said throat section beingspaced from said opposite end a distance such that said throat sectionreceives the closed end of a coupled like cartridge in projectingrelationship therein; and a rigid closure means slidably seated in saidthroat section for longitudinal movement therein with said closure meansbeing adapted to be a'butted by the closed end of a like cartridge uponprojection into said throat section so that said closure means is wedgedin said throat section in fluid-tight engagement therewith as couplingis being effected between said cartridge and said like cartridge.

2. The cartridge of claim 1 including detent means tfor locking saidclosure means in said throat section comprising an inwardly extendingrib circumferentially disposed on the inner wall of said throat sectionon the upper portion thereof adjacent to said opposite end of saidcartridge.

3. The cartridge of claim 2 wherein said cartridge is filled with anexplosive.

4. An explosive cartridge for end-to-end coupling with like cartridgesinto an explosive column comprising a selfsustaining elongated tubularcontainer having an integral closed end nose portion and an oppositeopen end, male screw thread means on said nose portion, female screwthread means on said open end with said female and said male threadmeans being complementary to each other to adapt said cartridge for saidcoupling to a like cartridge, a reduced throat section defining atruncated cone tapering inwardly of said cartridge toward said closedend with said throat section being reduced relative to adjacent portionsof said cartridge and spaced from, both, said closed end and said openend, said throat section being spaced from said open end a distance Suchthat when said female screw thread means and said open end receive thenose section of a like cartridge the closed end of the nose portionthereof projects into said throat section; and a rigid closure meansslidably seated in said throat section for longitudinal movementtherein, said closure means being adapted to be abutted by the closedend of said like cartridge upon projection into said throat section sothat said closure means is wedged in said throat section in fluid-tightengagement therewith as coupling is being effected between saidcartridge and said like cartridge.

5. The cartridge of claim 4 wherein said closure means comprises acup-shaped member having outwardly tapered side walls with the concavitythereof disposed adjacent said open end.

6. The cartridge of claim 5 including detent means for locking saidclosure means in said throat section comprising a circumferentiallyextending rib on the inner wall of said throat section at the upper endthereof adjacent said open end.

7. The cartridge of claim 6 wherein said cartridge comprises a containerformed of water-inert polymeric material.

8. An explosive cartridge for end-to-end coupling with like cartridgesinto an explosive column comprising a selfsustaining cylindricalcontainer of polymeric material and having an integral closed end and anopposite open end, male coupling means on the outer wall of saidcontainer adjacent said closed end, female coupling means on the innerwall of said container adjacent said open end with said female couplingmeans being complementary to said male coupling means to adapt saidcartridge for coupling to a like cartridge, a reduced throat sectiondefining a truncated cone tapering inwardly of said cartridge towardsaid closed end having said male coupling means, said throat sectionbeing reduced relative to adjacent portions of said cartridge and spacedfrom, both, said closed end and said open end; said throat section beingspaced from said open end a distance such that the said throat sectionreceives the distal portion of the closed end of said like cartridgewhen coupled to said cartridge so that the said distal end projects intosaid throat section; and a rigid closure means slidably seated in saidthroat section for longitudinal wedging movement therein, said closuremeans being adapted to be abutted by said distal end of said likecartridge upon projection into said throat section so that the saidclosure means is forceably driven thereby into wedged sealing engagementwith said throat section as coupling is being effected between saidcartridge and said like cartridge.

9. The cartridge of claim 8 including detent means for locking saidclosure means in said throat section comprising an inwardly extendingrib circumferentially disposed on the inner wall of said throat sectionat the end portion thereof adjacent the open end of said cartridge.

10. The cartridge of claim 9 wherein said closure means comprises arigid cup-shaped member having outwardly tapered sidewalls conforming tothe inner wall of said throat section with the concavity of said memberbeing disposed adjacent said open end of said cartridge.

11. The cartridge of claim 10 wherein said container is filled with anitrocarbonitrate explosive composition.

12. The cartridge of claim 10 wherein said container is filled with anexplosive comprising ammonium nitrate.

13. The cartridge of claim 9 wherein said container is filled with anexplosive.

14. The cartridge of claim 13 wherein said explosive is anitrocarbonitrate composition.

15. The cartridge of claim 13 wherein said explosive comprises ammoniumnitrate.

16. The cartridge of claim 8 including a lower nose portion formed ofsaid container and defining its said closed end and wherein said malecoupling means are external male screw threads formed of said containerand disposed externally on said nose portion, and an upper portionformed of said container and defining its said open end and wherein saidfemale coupling means are internal female screw threads disposed on theinner Wall of said upper portion, said upper portion having its saidinner wall complementary to the outer wall of said nose portion wherebysaid upper portion is adapted to be coupled to a nose portion of a likecartridge so that its nose portion projects into said throat section.

17. The cartridge of claim 16 including external radial gussets formedof said container and extending between the external walls of saidthroat section and said container with said gussets disposed at thejunction of said throat section with the adjacent portion of saidcontainer disposed between said throat section and said nose portion.

18. The cartridge of claim 17 including detent means for locking saidclosure means in said throat section comprising an inwardly extendingrib circumferentially disposed on the inner wall of said throat sectionat the end portion thereof adjacent the open end of said cartridge.

19. The cartridge of claim 18 wherein said closure means comprises arigid cup-shaped member having outwardly tapered side walls conformingto the inner wall of said throat section with the concavity of saidmember being disposed adjacent the said open end of said cartridge.

29. The cartridge of claim 19 wherein said container is filled with anitrocarbonitrate explosive composition.

21. The cartridge of claim 19 wherein said container is filled with anexplosive composition comprising ammonium nitrate.

22. The cartridge of claim w wherein said cartridge comprises acontainer formed of polymeric material and said container is filled withan explosive, and including a booster primer unit coupled to the upperportion of said container, said unit comprising a self-sustainingcylindrical container of polymeric material having a lower closed endand an upper open end, an integral lower portion formed of said unit anddefining its said closed end, external male screw threads disposed onthe external wall of said units lower portion and adapted to be coupledinto and with the female screw threads in the said upper portion of saidcartridge to project the closed end of said unit into said throatsection in driving engagement with said closure member, a detonator wellcomprising a portion of said closed end of said unit recessed inwardlythereof, a longitudinal groove in the external wall of said unitcommunicating with said well, an explosive booster charge in said unit,closure means secured to the said open end of said unit, a detonatordisposed in said well, and an electric lead wire extending in saidgroove to said detonator.

23. A blasting column comprising a plurality of cartridges coupled inend-to-end relationship with said cartridges filled with an explosive,and a blasting unit coupled to an endmost cartridge each of saidcartridges comprising a cartridge formed of (a) a self-sustainingcylindrical container of polymeric material and (i) having an integralclosed end and (ii) an opposite open end,

(b) a lower nose portion formed of said cartridge and defining its saidclosed end,

(c) male coupling means defining external male screw threads with (i)said male coupling means formed of said cartridge and (ii) disposedexternally on said nose portion, ((1) an upper portion formed of saidcartridge and (i) defining its said opposite open end, (e) femalecoupling means defining internal female screw threads (i) disposed onthe inner wall of said upper portion, with (ii) said upper portionhaving its said inner wall complementary to the outer wall of said noseportion whereby (iii) said upper portion is adapted to be coupled to anose portion of a like cartridge, (f) a reduced throat section defininga truncated cone tapering inwardly of said cartridge toward said closedend having said male coupling means,

(i) said throat section being reduced relative to adjacent portions ofsaid cartridge and (ii) spaced from, both, said closed end and said openend, with (iii) said throat section spaced from said open end a distancesuch that said throat section receives the distal portion of the closedend of said like cartridge when coupled to said cartridge so that thedistal end projects into said throat section,

(g) a rigid closure means slidably seated in said throat section forlongitudinal wedging movement therein, said closure means comprising (i)a rigid cup-shaped member having outwardly tapered side walls conformingto the inner wall of said throat section with the concavity of saidmember being disposed adjacent the said open end of said cartridge, and

(ii) said closure means being adapted to be abutted by the said distalportion of said like cartridge upon projection into said throat sectionso that said closure means is forceably driven thereby into wedgedsealing engagement with said throat section as coupling is beingeffected between said cartridge and said like cartridge,

('h) external radial gussets formed of said cartridge extending betweenthe external walls of said throat section and said cartridge with (i)said gussets disposed at the junction of said throat section with theadjacent portion of said cartridge disposed between said throat sectionand said nose portion, and

(i) detent means for locking said closure means in said throat sectioncomprising (i) an inwardly extending rib circumferentially disposed onthe inner wall of said throat section at the end portion thereofadjacent the open end of said cartridge; and

(j) said blasting unit comprising a self-sustaining container ofpolymeric material having (i) a lower closed end and (ii) an upper openend, (k) an integral lower portion formed of said unit and (i) definingits said closed end, (1) external male screw threads disposed on theexternal wall of said units lower portion and (i) adapted to be coupledinto and with the female screw threads in the said upper portion of saidcartridge to project the closed end of said unit into said throatsection in driving engagement with said closure means, (m) a detonatorwell comprising a portion of said closed end of said unit recessedinwardly thereof, (n) a longitudinal groove in the external Wall of saidunit communicating with said well,

(0) an explosive booster charge in said unit,

(p) a closure means secured to said open end of said unit,

(q) a detonator disposed in said well, and

(r) an electric lead wire extending in said groove to said detonator.

References Cited by the Examiner UNITED STATES PATENTS 1,776,487 9/1930Callas 102--24 X 2,345,887 4/ 1944 Rothr-ock l0224 X 2,887,953 5/1959Mager l0224 3,013,492 12/1961 Sexton l0224 3,082,689 3/1963 Griffith etal. l0224 3,185,091 5/1965 Hamilton l0224 3,185,092 5/1965 Hamiltonl0224 3,186,340 6/1965 Foster l0224 BENJAMIN A. BORCHELT, PrimaryExaminer.

R. V. LOTTMANN, Assistant Examiner.

1. IN A HOLLOW CYLINDRICAL CARTRIDGE HAVING ONE CLOSED END MALE COUPLINGMEANS ON THE ONE CLOSED END THEREOF AND FEMALE COUPLING MEANS ON THEOPPOSITE END THEREOF FOR COUPLING TO LIKE CARTRIDGES INTO AN EXPLOSIVETRAIN, THE IMPROVEMENT COMPRISING, A REDUCED THROAT SECTION DEFINING ATRUNCATED CONE TAPERING INWARDLY OF SAID CARTRIDGE TOWARD SAID CLOSEDEND HAVING SAID MALE COUPLING MEANS WITH SAID THROAT SECTION BEINGREDUCED RELATIVE TO ADJACENT PORTIONS OF SAID CARTRIDGE AND SPACED FROM,BOTH, SAID CLOSED END AND SAID OPPOSITE END, SAID THROAT SECTION BEINGSPACED FROM SAID OPPOSITE END A DISTANCE SUCH THAT SAID THROAT SECTIONRECEIVES THE CLOSED END OF A COUPLED